How could I create a 3 Dimensional scribble or doodle?
There are a couple ways you could go about this.
Curve object

Add a curve object (I used a path, ⇧ ShiftA&gt; Curve &gt; Path)

In edit mode (↹ Tab), extrude a vertex around randomly (⎈ Ctrl LMB is a fast way to extrude a vertex many times)

Use the Randomize operator in edit mode to further increase randomness (Space&gt; Randomize)



Grease Pencil

Enable Continuous Draw in 3D view &gt; Tool Shelf &gt; Grease Pencil and press Draw to start drawing

Draw scribbles while rotating the view at intervals



Once you are satisfied with your scribble, convert it to a curve object with the Convert button in the tool shelf: